Evidence released by the U.S. Department of Agriculture's Agricultural Research Service suggests that the use of switchgrass as a viable cellulosic ethanol feedstock may be gaining credibility.
"It would largely depend on the size of the ethanol plant, but switchgrass from an economic perspective can be manageable," ARS research agronomist Marty Schmer says. "It can work."
Schmer was one of several guest speakers at the Biomass 2009 Power, Fuels and Chemicals Workshop, recently held in Grand Forks, N.D., and sponsored by the University of North Dakota's Energy and Environmental Research Center.
Current thinking
Previous opinions of some researchers and at least one corn ethanol plant manager in Minnesota have held that delivery of the amount of switchgrass needed each day to fuel and feed an ethanol plant would be logistically impossible. But these opinions were held forth two years ago when the possibility of cellulosic ethanol still was very uncertain.
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Since then, cellulosic technologies have matured. Several pilot plants, including one in Denmark, have proved that cellulosic processing can be made viable.
The new thinking is that switchgrass can be a viable feedstock when used in conjunction with other soft-fiber crop residues such as wheat straw or corn stover.
"Multiple feedstocks will make it economically viable for most cellulosic ethanol plants," Schmer says.
According to one industry source, a relatively small, 20 million-gallon plant would require 1,200 tons of this mixed-feedstock be delivered each day. This is equivalent to about 2,000 large, square bales.
There are some benefits to using switchgrass as feedstock. Perhaps foremost is that it can be grown on CRP acres, which now number more than 30 million. This would allow food crop acreage to remain stable. The Environmental Protection Agency recently predicted that 2.8 million CRP acres will be planted to switchgrass by 2022.
Schmer says the grass also tends to generate low greenhouse gas emissions and can sequester large amounts of carbon in the soil, which could make carbon credit funds a possibility for producers.
"And it can provide fairly stable yields across a large geographical region, which would be important for a cellulosic bio-refinery," he says.
Industry interest
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Interest is growing.
Larry Johnson, a business development consultant, is part of a team attempting to secure funding for three of these cellulosic plants, one of which is targeted for east-central North Dakota. He has been in the ethanol industry for nearly 25 years and has participated in building several grain ethanol plants in the Midwest. He now represents a Danish company, Inbicon, which has been producing cellulosic ethanol from wheat straw feedstock for seven years at its pilot plant in Copenhagen, Denmark.
"They've created a technology to turn wheat straw and corn stover and other soft crops like switchgrass into ethanol," he says. "We make ethanol and molasses out of their (released) sugars and also lignin for the boiler fuel."
The company had wanted to complete construction of its first U.S. plant this year, but lining up the funding currently is a Catch-22 situation for Johnson because of the economic downturn.
"We have a huge financing issue. You can't get a plant financed until you have a guarantee of the feedstock," Johnson says. "You can't get the feedstock from the farmer until they know they've got a market for it."
For now, he's hoping to break ground on the North Dakota plant next year. He expects it would run at first on pure wheat straw, but eventually incorporate corn stover and switchgrass.
